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Questions in chemistry

[Done] Complete the following sentences: 1. An explosion that occurs at the end of a massive star's life is a _________. 2. A ___________ is a large cloud of gas and dust in space. 3. A low- or medium-mass star becomes a ____________ at the end of its life. 4. A ___________ appears to emit regular bursts of radio waves. 5. A ___________ forms from the leftover material from a supernova; it may contain as much as three times the mass of the sun.

[Done] True or false: The density of a substance varies with samples of that substance.

[Done] Which of these are a Brønsted acid, a Brønsted base, or both a Brønsted acid and a Brønsted base? - [tex]\text{PO}_4^{3-}[/tex] - [tex]\text{ClO}_2^{-}[/tex] - [tex]\text{NH}_4^{+}[/tex] - [tex]\text{HCO}_3^{-}[/tex] - [tex]\text{H}_2\text{PO}_4^{-}[/tex]

[Done] Describe an advantage of using dry ice to ship cardboard cartons of ice cream over long distances.

[Done] If you were writing an electron configuration for a bromine atom, which elemental symbol would you place in the bracket?

[Done] What is the coefficient in the formula \(6C_6H_{12}O_6\)?

[Done] How many protons, electrons, and neutrons are in [tex]I^{-}[/tex] and [tex]Li^{+}[/tex]?

[Done] How do scientists apply emission spectra to investigate the chemical composition of stars? Write a one-page essay.

[Done] What is formed when two atoms of bromine bond together?

[Done] Why is there so much nitrogen in the atmosphere?